diff --git a/src/Convert/DuplicateGenvar.hs b/src/Convert/DuplicateGenvar.hs
index 97c17fc..2c2ee71 100644
--- a/src/Convert/DuplicateGenvar.hs
+++ b/src/Convert/DuplicateGenvar.hs
@@ -6,7 +6,7 @@
 
 module Convert.DuplicateGenvar (convert) where
 
-import Control.Monad.State
+import Control.Monad.State.Strict
 import qualified Data.Set as Set
 
 import Convert.Traverse
diff --git a/src/Convert/EmptyArgs.hs b/src/Convert/EmptyArgs.hs
index 8166085..2e25403 100644
--- a/src/Convert/EmptyArgs.hs
+++ b/src/Convert/EmptyArgs.hs
@@ -8,7 +8,7 @@
 
 module Convert.EmptyArgs (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import qualified Data.Set as Set
 
 import Convert.Traverse
diff --git a/src/Convert/Enum.hs b/src/Convert/Enum.hs
index a1be28b..bd2653d 100644
--- a/src/Convert/Enum.hs
+++ b/src/Convert/Enum.hs
@@ -19,7 +19,7 @@
 
 module Convert.Enum (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import Data.List (elemIndices)
 import qualified Data.Set as Set
 
diff --git a/src/Convert/FuncRoutine.hs b/src/Convert/FuncRoutine.hs
index 1a3357b..595c8d4 100644
--- a/src/Convert/FuncRoutine.hs
+++ b/src/Convert/FuncRoutine.hs
@@ -10,7 +10,7 @@
 
 module Convert.FuncRoutine (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import qualified Data.Set as Set
 
 import Convert.Traverse
diff --git a/src/Convert/Interface.hs b/src/Convert/Interface.hs
index 6e383f7..7f25c99 100644
--- a/src/Convert/Interface.hs
+++ b/src/Convert/Interface.hs
@@ -8,7 +8,7 @@ module Convert.Interface (convert) where
 
 import Data.List (isPrefixOf)
 import Data.Maybe (mapMaybe)
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import qualified Data.Map.Strict as Map
 
 import Convert.Scoper
diff --git a/src/Convert/Jump.hs b/src/Convert/Jump.hs
index 5812238..67dfb4c 100644
--- a/src/Convert/Jump.hs
+++ b/src/Convert/Jump.hs
@@ -10,8 +10,8 @@
 
 module Convert.Jump (convert) where
 
-import Control.Monad.State
-import Control.Monad.Writer
+import Control.Monad.State.Strict
+import Control.Monad.Writer.Strict
 
 import Convert.Traverse
 import Language.SystemVerilog.AST
diff --git a/src/Convert/KWArgs.hs b/src/Convert/KWArgs.hs
index 549f41f..c357a45 100644
--- a/src/Convert/KWArgs.hs
+++ b/src/Convert/KWArgs.hs
@@ -10,7 +10,7 @@
 module Convert.KWArgs (convert) where
 
 import Data.List (elemIndex, sortOn)
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import qualified Data.Map.Strict as Map
 
 import Convert.Traverse
diff --git a/src/Convert/Logic.hs b/src/Convert/Logic.hs
index 2e54cfa..f58732e 100644
--- a/src/Convert/Logic.hs
+++ b/src/Convert/Logic.hs
@@ -25,8 +25,8 @@
 
 module Convert.Logic (convert) where
 
-import Control.Monad.State
-import Control.Monad.Writer
+import Control.Monad.State.Strict
+import Control.Monad.Writer.Strict
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 
diff --git a/src/Convert/NamedBlock.hs b/src/Convert/NamedBlock.hs
index abf5724..9a16e27 100644
--- a/src/Convert/NamedBlock.hs
+++ b/src/Convert/NamedBlock.hs
@@ -10,7 +10,7 @@
 
 module Convert.NamedBlock (convert) where
 
-import Control.Monad.State
+import Control.Monad.State.Strict
 import qualified Data.Set as Set
 
 import Convert.Traverse
diff --git a/src/Convert/NestPI.hs b/src/Convert/NestPI.hs
index 4ca537e..5525dd0 100644
--- a/src/Convert/NestPI.hs
+++ b/src/Convert/NestPI.hs
@@ -6,7 +6,7 @@
 
 module Convert.NestPI (convert, reorder) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import Data.Maybe (mapMaybe)
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
diff --git a/src/Convert/Package.hs b/src/Convert/Package.hs
index 266e939..0019630 100644
--- a/src/Convert/Package.hs
+++ b/src/Convert/Package.hs
@@ -25,8 +25,8 @@
 
 module Convert.Package (convert) where
 
-import Control.Monad.State
-import Control.Monad.Writer
+import Control.Monad.State.Strict
+import Control.Monad.Writer.Strict
 import qualified Data.Map.Strict as Map
 import qualified Data.Set as Set
 
diff --git a/src/Convert/ParamType.hs b/src/Convert/ParamType.hs
index b0e5f70..e7a1bf0 100644
--- a/src/Convert/ParamType.hs
+++ b/src/Convert/ParamType.hs
@@ -7,7 +7,7 @@
 
 module Convert.ParamType (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import Data.Either (isLeft)
 import Data.Maybe (isJust, isNothing, fromJust)
 import qualified Data.Map.Strict as Map
diff --git a/src/Convert/Scoper.hs b/src/Convert/Scoper.hs
index d8e3be9..eaa45a6 100644
--- a/src/Convert/Scoper.hs
+++ b/src/Convert/Scoper.hs
@@ -42,7 +42,7 @@ module Convert.Scoper
     , scopeModuleItemT
     ) where
 
-import Control.Monad.State
+import Control.Monad.State.Strict
 import Data.Functor.Identity (runIdentity)
 import Data.Maybe (isNothing)
 import qualified Data.Map.Strict as Map
diff --git a/src/Convert/SizeCast.hs b/src/Convert/SizeCast.hs
index b65a406..e0d2b87 100644
--- a/src/Convert/SizeCast.hs
+++ b/src/Convert/SizeCast.hs
@@ -7,7 +7,7 @@
 
 module Convert.SizeCast (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import Data.List (isPrefixOf)
 
 import Convert.ExprUtils
diff --git a/src/Convert/StarPort.hs b/src/Convert/StarPort.hs
index b5f8dea..8b7a40b 100644
--- a/src/Convert/StarPort.hs
+++ b/src/Convert/StarPort.hs
@@ -6,7 +6,7 @@
 
 module Convert.StarPort (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import qualified Data.Map.Strict as Map
 
 import Convert.Traverse
diff --git a/src/Convert/Traverse.hs b/src/Convert/Traverse.hs
index 8d4a859..11e855f 100644
--- a/src/Convert/Traverse.hs
+++ b/src/Convert/Traverse.hs
@@ -98,8 +98,8 @@ module Convert.Traverse
 ) where
 
 import Data.Functor.Identity (Identity, runIdentity)
-import Control.Monad.State
-import Control.Monad.Writer
+import Control.Monad.State.Strict
+import Control.Monad.Writer.Strict
 import Language.SystemVerilog.AST
 
 type MapperM m t = t -> m t
diff --git a/src/Convert/UnbasedUnsized.hs b/src/Convert/UnbasedUnsized.hs
index 8e52ebb..892323b 100644
--- a/src/Convert/UnbasedUnsized.hs
+++ b/src/Convert/UnbasedUnsized.hs
@@ -17,7 +17,7 @@
 
 module Convert.UnbasedUnsized (convert) where
 
-import Control.Monad.Writer
+import Control.Monad.Writer.Strict
 import Data.Maybe (catMaybes)
 import qualified Data.Map.Strict as Map
 
diff --git a/src/Convert/UnpackedArray.hs b/src/Convert/UnpackedArray.hs
index f869a9a..2fa93b3 100644
--- a/src/Convert/UnpackedArray.hs
+++ b/src/Convert/UnpackedArray.hs
@@ -14,7 +14,7 @@
 
 module Convert.UnpackedArray (convert) where
 
-import Control.Monad.State
+import Control.Monad.State.Strict
 import qualified Data.Set as Set
 
 import Convert.Scoper
diff --git a/src/Language/SystemVerilog/Parser.hs b/src/Language/SystemVerilog/Parser.hs
index 20a586d..50c0208 100644
--- a/src/Language/SystemVerilog/Parser.hs
+++ b/src/Language/SystemVerilog/Parser.hs
@@ -6,7 +6,7 @@ module Language.SystemVerilog.Parser
     ) where
 
 import Control.Monad.Except
-import Control.Monad.State
+import Control.Monad.State.Strict
 import qualified Data.Map.Strict as Map
 import Language.SystemVerilog.AST (AST)
 import Language.SystemVerilog.Parser.Lex (lexStr)
diff --git a/src/Language/SystemVerilog/Parser/Parse.y b/src/Language/SystemVerilog/Parser/Parse.y
index 514f95c..a166ea6 100644
--- a/src/Language/SystemVerilog/Parser/Parse.y
+++ b/src/Language/SystemVerilog/Parser/Parse.y
@@ -16,7 +16,7 @@
 module Language.SystemVerilog.Parser.Parse (parse) where
 
 import Control.Monad.Except
-import Control.Monad.State
+import Control.Monad.State.Strict
 import Data.Maybe (fromMaybe)
 import Language.SystemVerilog.AST
 import Language.SystemVerilog.Parser.ParseDecl
diff --git a/src/Language/SystemVerilog/Parser/Preprocess.hs b/src/Language/SystemVerilog/Parser/Preprocess.hs
index 3ad5d1b..177362a 100644
--- a/src/Language/SystemVerilog/Parser/Preprocess.hs
+++ b/src/Language/SystemVerilog/Parser/Preprocess.hs
@@ -14,7 +14,7 @@ module Language.SystemVerilog.Parser.Preprocess
     ) where
 
 import Control.Monad.Except
-import Control.Monad.State
+import Control.Monad.State.Strict
 import Data.Char (ord)
 import Data.List (dropWhileEnd, tails, isPrefixOf, findIndex)
 import Data.Maybe (isJust, fromJust)